Whether talking to a friend, family, a scholar, a teacher, or any other person one much always keep the following basic priinciples in mind. Do not always assume that because you or the other person has "free call time" it is always convenient or appropriate for your to call. Keep in mind:
1. Always identify yourself by saying your name unless it is someone very close to you - indeed there maybe more than one Ayesha or Abdullah the person you are calling knows, and voices are not always easy to distinguish by all.
2. Ensure it is convenient for the person to speak and that they are not engaged in other activities.
3. Do not engage in conversation or answer questions until you know who is calling - lest you disclose something you shouldn't.
4. Choose the right time for your call, whether calling relatives, friends, employees or officials - avoid meal times and prayer times in particular.
5. Make your conversation brief and to the point, so it will not interfere with thier business or other calls they themselves have to make or receive (Particularly important with Shaykhs and such like - do not make a 20 minute story about a simple question, be succinct and try to mention only that which is relevant).
6. When conversing with a member of the opposite sex, for an appropriate reason (eg: a teacher, scholar etc) then be sure not to go off topic, and maintain a level of respect and formality.
7. Sisters - If you have a naturally soft voice, try to make it more 'rough' - so as not to encourage the one who may have illness in thier heart. Indeed in the extra effort this involves will come extra reward inshaAllah for wanting to please Allah (سبحانه وتعالى).